Specifications

Curtis PMC 1223/33, 1225/35, 1227/37 Manual
A-11
APPENDIX A: GLOSSARY
Smooth, stepless operation
Like all Curtis PMC 1200 Series controllers, 1223/33, 1225/35, 1227/37 models
allow superior operator control of the vehicle’s drive motor speed. The amount
of current delivered to the motor is set by varying the “on” time (duty cycle) of
the controller’s power MOSFET transistors. This technique—pulse width modu-
lation (PWM)—permits silent, stepless operation.
Speed interlocks
The 1223/33, 1225/35, and 1227/37 controllers come standard with speed
interlocks. The speed interlocks prevent the speed parameters from being inad-
vertently programmed to give abnormal operating characteristics. The speed
interlocks can be disabled at the factory, if so desired—see Section 4, page 45.
However, this is not recommended unless a specific application requires that the
existing speed interlock relationships be violated.
Speed settings
There are two upper-limit speed settings in each mode: “maximum” and “mini-
mum.” The “maximum speed” setting defines the highest controller output at full
throttle with the speed limit pot in its maximum speed position. The “minimum
speed” setting defines the highest controller output at full throttle with the speed
limit pot in its minimum speed position. The “maximum” and “minimum”
speeds are programmable independently for Mode 1 and Mode 2—see Section 3,
page 30.
Static-return-to-off (SRO)
The SRO feature prevents the vehicle from being started when “in gear.” SRO
checks the sequencing of KSI (and power enable input, if a power enable switch
is used) relative to either direction (Type 1) or relative to forward only (Type 2).
The controller can be programmed to provide Type 0 (no SRO), Type 1 SRO, or
Type 2 SRO—see Section 3, page 43.
Temperature compensation
The 1223/33, 1225/35, 1227/37 controllers are specified to operate at their
temperature-compensated current limits for one full minute. They employ
temperature compensation to maintain consistent current limit and IR compen-
sation levels. This minimizes performance variation resulting from changes in
controller or ambient temperatures. There is, however, a small rolloff in the